The present invention relates generally to a tool and method for creating a seat in jewelry for receiving a gemstone, and more particularly to such a tool shaped to more precisely form the seat to the gemstone.
Gemstones are set using a cutting tool to form a seat in a setting of the jewelry. The gemstone is positioned in the seat and the setting is deformed around the gemstone to secure it therein. Though successful, the methods and tools utilized in the prior art do not fully address structural considerations, alloy strengths, or stress-related fatigue with regard to the settings used to secure the gemstones. As a result, when settings are prepared using the methods and tools of the prior art, a substantial risk of weakening the structural integrity of the setting exists. Additionally, there is a significant risk that as the setting is being manually deformed, the crown and girdle of the gemstone could be damaged.
Typically, in the methods of the prior art, as illustrated in FIG. 1A, a notch 200 having two surfaces is cut into a setting, such as a prong-type setting having prongs 9, and a gemstone 3 is set into the notch, as shown in FIG. 1B. The gemstone has a crown, a pavilion, and a girdle between the crown and pavilion. As illustrated in FIG. 1B, the notch 200 must be cut deep enough to accommodate the girdle of the gemstone. When the girdle is positioned against the inner face of the setting, a gap is present between the crown of the gemstone being set and the setting in the notch. Once the gemstone is positioned, the setting is manually deformed and pressed against the crown of the gemstone, thus closing the gap and securing the gemstone within the setting. Referring to FIG. 1B, it may be seen that the notch 200 is V-shaped, but that the profile of the gemstone is polygonal. In order to receive the gemstone in the notch without a substantial gap between the inner surface of the notch and the girdle, the angle of the notch is substantially greater than the angle between the crown and pavilion of the gemstone. Thus, when the setting is bent to secure the gemstone in the notch, substantial plastic deformation of the setting occurs, as illustrated by the cross-hatched, triangular area 100 in FIG. 1C. A bending movement causes the inner face of the setting to be compressed, while the outer edge of the setting is elongated. These weakened setting areas are subject to chemical attack and reduced structural strength along grain boundaries.
Additionally, the present setting methods increase the potential of damage to the gemstone being set. Using the methods of the prior art, a setting prepared and manually deformed to secure the gemstone in place pinches the gemstone obliquely from above and below, but not uniformly on all sides of the gemstone being set. A gap, as shown in FIGS. 1B and 1C is created between the girdle of the gemstone and the setting. When the setting is manually deformed to secure the gemstone, the pressure applied to the gemstone on both sides of the gap can weaken the stone and cause this area of the gemstone to break, especially if the grain of the crystalline structure is aligned with the setting at a cleavage point of the stone.